An immunohistochemical study of p53 protein in the different histological subtypes of gastric carcinoma

Histopathological, Molecular, and Genetic Profile of Hereditary Diffuse Gastric Cancer: Current Knowledge and Challenges for the Future

Familial clustering is seen in 10 % of gastric cancer cases and approximately 1-3 % of gastric cancer arises in the setting of hereditary diffuse gastric cancer (HDGC). In families with HDGC, gastric cancer presents at young age. HDGC is predominantly caused by germline mutations in CDH1 and in a minority by mutations in other genes, including CTNNA1. Early stage HDGC is characterized by a few, up to dozens of intramucosal foci of signet ring cell carcinoma and its precursor lesions. These include in situ signet ring cell carcinoma and pagetoid spread of signet ring cells. Advanced HDGC presents as poorly cohesive/diffuse type carcinoma, normally with very few typical signet ring cells, and has a poor prognosis. Currently, it is unknown which factors drive the progression towards aggressive disease, but it is clear that most intramucosal lesions will not have such progression.Immunohistochemical profile of early and advanced HDGC is often characterized by abnormal E-cadherin immunoexpression, including absent or reduced membranous expression, as well as "dotted" or cytoplasmic expression. However, membranous expression of E-cadherin does not exclude HDGC. Intramucosal HDGC (pT1a) presents with an "indolent" phenotype, characterized by typical signet ring cells without immunoexpression of Ki-67 and p53, while advanced carcinomas (pT > 1) display an "aggressive" phenotype with pleomorphic cells, that are immunoreactive for Ki-67 and p53. These features show that the IHC profile is different between intramucosal and more advanced HDGC, providing evidence of phenotypic heterogeneity, and may help to define predictive biomarkers of progression from indolent to aggressive, widely invasive carcinomas.

Assessment of Cell Proliferation in Benign, Premalignant and Malignant Skin Lesions

A deeper understanding of the variance of epidermal cell proliferation may eventually increase the reproducibility of diagnostic classification. A prospective study of 46 consecutive, unselected biopsies from benign (keratoacanthoma n=14), premalignant (actinic keratosis n=15 and Bowen disease n=10) and malignant (squamous cell carcinoma n=7) skin lesions was studied to assess the presence and extent of differences in expression of the proliferation marker Ki-67 using a monoclonal antibody directed against a c-DNA defined subsegment (MIB-1) and a noncross-linking, proprietary fixative BoonFix. MIB-1 was expressed in the adjacent, non-affected skin in a scattered to confluent linear pattern in the basal/suprabasal cell layer. In actinic keratosis, MIB-1 expression, in addition to basal/suprabasal layers, extended to mid-zones of the epidermis. An interesting feature in actinic keratosis as well as in Bowen disease was the expression of MIB-1 in the epithelium lining the hair follicles. In Bowen disease, MIB-1 was observed throughout the full thickness of the epidermis, unequivocally separating this entity from others under study. In invasive squamous cell carcinoma, MIB-1 expression was not consistent between and within cases. MIB-1 positivity was variably found in all layers of the epidermis, but showed a chaotic and haphazard pattern with total loss of polarity. Keratoacanthoma cases showed highly variable MIB-1 expression, ranging from no expression to expression in both basal/suprabasal and mid-zone layers of the epidermis. These results warrant further study of modulation of cell proliferation in actinic keratosis.

Predictive value of p53 and pRb expression in superficial bladder cancer patients treated with BCG and interferon-alpha

BACKGROUND

Nuclear p53 and retinoblastoma protein (pRb) were reported to be poor prognostic indicators for transitional cell carcinoma of the bladder. The authors sought to determine the prognostic value of nuclear p53 and pRb in superficial bladder transitional cell carcinoma patients who were treated with intravesical bacille Calmette-Guerin (BCG) or BCG with interferon-alpha (IFN-alpha).

METHODS

A prospective histological review was performed for 80 superficial bladder transitional cell carcinoma patients who underwent postresection intravesical regimes of BCG (81 mg, n = 33 or 27 mg, n = 20) or BCG (27 mg) with IFN-alpha (n = 27), and followed for a mean of 4.5 years. Hematoxylin and eosin (H & E) and immunoperoxidase staining were performed on tissue sections. Nuclear p53 and pRb immunoreactivity were assessed semiquantitatively, by using a combination of staining extent and intensity, to categorize overexpression or underexpression. Data were analyzed by using chi-square analysis, multiple logistic regression, and Kaplan-Meier curves.

RESULTS

pRb expression was not associated with patient outcome after BCG-alone therapy, but pRb underexpression was significantly associated with BCG nonresponse and tumor recurrence (P = .047) after BCG and IFN-alpha (BCG + IFN-alpha) therapy. Low-grade tumors were associated with pRb overexpression, with or without nuclear p53 underexpression (P = .019; P = .043, respectively). p53 expression alone or in combination with pRb expression had no significant relation with tumor response to BCG alone or BCG + IFN-alpha with respect to recurrence, progression, or cancer-specific death.

CONCLUSIONS

Nuclear pRb underexpression may be predictive of nonresponse and cancer recurrence after intravesical BCG + IFN-alpha therapy. Nuclear p53 expression or its combination with pRb expression is not associated with post-BCG clinical outcome, so p53 expression or p53 with pRb expression should not be used to influence decisions concerning BCG-alone or BCG + IFN-alpha therapy.

Relationship between E-cadherin gene mutation and p53 gene mutation, p53 accumulation, Bcl-2 expression and Ki-67 staining in diffuse-type gastric carcinoma

E-cadherin mutations are found in 50% of diffuse-type gastric carcinoma, but not in intestinal gastric carcinoma. Because cell-cell adhesion mediated by E-cadherin plays an important role in epithelial cell survival, E-cadherin mutations could alter the apoptotic behavior of tumor cells. p53 and Bcl-2 family members are also important regulators of cellular apoptosis. This is the first study that investigates the relationship between E-cadherin gene mutation and p53 gene mutation, p53 accumulation, Bcl-2 expression, and Ki-67 expression in diffuse-type gastric carcinoma (24 cases, E-cadherin mutation status: wild-type in 8 patients and mutant in 16 patients). The mutation status of exons 5-8 of p53 was analyzed by denaturing high pressure liquid chromatography (DHPLC) in formalin-fixed, paraffin-embedded tumor sections, followed by direct sequencing of cases with aberrant chromatographic patterns. p53 mutations were found in 1 of 8 tumors without E-cadherin mutation (12.5%) and in 1 of 16 tumors with E-cadherin mutation (6.3%), a difference that was not statistically significant (p = 1.00). p53 accumulation was found in 8 of 24 tumors (33.3%) by immunohistochemical staining. p53 accumulation was significantly more frequent in tumors without E-cadherin mutations (5 of 8 tumors, 62.5%) than in gastric carcinoma tissues with E-cadherin mutations (3 of 16 tumors, 18.8%, p = 0.03). Bcl-2 staining was not observed in gastric carcinoma cells without E-cadherin mutations, but was detectable in 5 of 16 tumors with E-cadherin mutations (31.3%), a difference that was not statistically significant (p = 0.13). No relationship was observed between Ki-67 staining and the E-cadherin mutation status (p = 1.00). These data suggest that the presence of E-cadherin mutations can significantly alter the accumulation of the apoptosis-regulating p53 protein, whereas no correlation with the p53 mutation status or with Ki-67 staining was observed.

Study of p53 immunostaining in the gastric epithelium of cagA-positive and cagA-negative Helicobacter pylori gastritis

BACKGROUND

p53 mutations are an early event in the multistep progression of gastric carcinoma. These mutations are often present in dysplastic and intestinal metaplastic gastric epithelium. However, the presence of immunohistochemically detectable p53 protein and p53 mutations in nondysplastic/nonmetaplastic gastric mucosa is more controversial. Recent reports have suggested that immunohistochemically detectable p53 protein may be present in the gastric epithelium of Helicobacter pylori gastritis. Furthermore, because cagA-positive H. pylori is associated with greater mucosal injury but decreased apoptosis, it would be interesting to determine if this phenotype is associated with greater immunostaining of p53, as the wild-type p53 gene helps to initiate apoptosis.

METHODS

One hundred thirty-five patients with H. pylori-associated gastritis were immunohistochemically stained for p53 and quantified for the extent and intensity of the staining using a semiquantitative method (0, nil staining; 6, extensive and strong staining). The cagA status of the organism was determined by Western blot.

RESULTS

Thirty-one patients (23%) showed strong p53 staining (> or = 4 of 6) in inflamed but otherwise normal gastric epithelium. In the 123 cagA-positive H. pylori gastritis patients, the average p53 staining score was 2.5 of 6. This is significantly higher than the corresponding score of 1.7 of 6 observed in the 12 patients with cagA-negative H. pylori gastritis (P = 0.04).

CONCLUSIONS

Our results indicate that p53 protein is immunohistochemically detectable even before gastric metaplastic/dysplastic change occurs. The results also suggest that cagA-positive H. pylori might be associated with greater p53 immunohistochemical staining. This would indicate that p53 immunohistochemical staining does not reliably differentiate between gastric dysplasia and reactive inflammatory atypia. If the p53 protein detected is a consequence of mutation, this would help to explain why cagA-positive H. pylori gastritis is associated with decreased apoptosis.

Diagnostic and prognostic tumor markers in the gastrointestinal tract

The gastrointestinal tract is the most common site of malignancies of any anatomic system in the body. An early detection of primary tumors of the bowel, pancreas, liver, stomach, and esophagus is often difficult in asymptomatic patients and for this reason these tumors are often detected at a relatively advanced stage, when symptoms lead to a diagnostic evaluation. Furthermore, gastrointestinal tract tumors have an extremely variable prognosis; thus, the identification of new prognostic parameters may be useful for selecting patients to more tailored therapies. In this work, the main molecular, genetic, tissular, and circulating tumor markers proposed for diagnosis and prognosis of gastrointestinal malignancies are reviewed and discussed.

An immunohistochemical study of p53 protein in cervical intraepithelial neoplasia and squamous cell carcinoma

p53 mutations are known to occur frequently in human cancers where they are considered to be an important event in the stepwise progression towards malignant transformation. It is therefore interesting to compare p53 expression in the uterine cervix for non-neoplastic/metaplastic squamous epithelium, cervical intraepithelial neoplasia (CIN) and invasive squamous cell carcinoma. One hundred and nineteen biopsied and resected specimens of the uterine cervix were stained with an anti-human p53 protein monoclonal antibody by the streptavidin-biotin immunoperoxidase method. Histologically these could be categorized into non-neoplastic/dysplastic conditions, including condyloma (34 cases), CIN 1-3 (66 cases) and invasive squamous cell carcinoma (19 cases). Fifty eight per cent (11/19) of the invasive squamous cell carcinomas and 11% (7/66) of the CIN stained positively for p53. Except for 3 cases of invasive squamous cell carcinoma, there was only sporadic intranuclear staining of less than 5% of the cells. No staining was observed in all non-neoplastic/metaplastic squamous epithelial cells. The pattern of p53 staining is significantly different for all 3 categories. However it is undetermined as to whether the positive immunoperoxidase staining is a direct consequence of p53 gene mutation or otherwise.